We found a new epileptic mutant rat and established a new epileptic rat strain, WER (Wakayama Epileptic Rat). In order to evaluate this strain as an animal model for human epilepsy, we analyzed type of seizures and electroencephalograms (EEG) at paroxysms. The WER rats spontaneously exhibited both tonic-clonic convulsion and absence-like seizures. The spike-and-wave discharges were characterized to 5.1±0.4Hz, average with standard error, in the absence-like seizures. Low-voltage fast waves were recorded in the tonic-clinic convulsions. These EEG patterns were resembled to those of human epilepsies. The onset of this disorder was estimated between 25 to 70 days of age. Some WER rats died suddenly between the onset period. Therefore sudden death at the seizure occurrence was assumed. After the sensitive period, the unexpected death was not observed and stable seizure occurrence was observed in the WER strain. Genetic analyses of the disorder siggested that the seizure occurrence was controlled by an autosomal single recessive gene. The penetrance of the gene was estimated to 86%. The SER and TM rats, and swe mice were reported that exhibited two types of seizures spontaneously by a single gene defect. The seizure phenotype of WER was resembled to those of the SER and TM rats, but other characteristics including morphological characters were not identical to those models. Therefore a new epileptic gene was suggested in the WER rats. The WER strain was suggested to be a useful animal model for inherited human epilepsy.